diff --git a/test/ref/Makefile b/test/ref/Makefile
index de9248ac7..2e7675b95 100644
--- a/test/ref/Makefile
+++ b/test/ref/Makefile
@@ -49,8 +49,8 @@ $(WORKDIR)/switch.%rg: CC65FLAGS += -Wc --all-cdecl
 # Also, yacc.c does some things that fail when stack operations are optimized.
 # Therefore, don't optimize them.
 #
-$(WORKDIR)/yacc.%rg: CC65FLAGS += -Wc --all-cdecl,--disable-opt,OptStackOps
-$(WORKDIR)/yaccdbg%prg: CC65FLAGS += -Wc --all-cdecl,--disable-opt,OptStackOps
+$(WORKDIR)/yacc.%rg: CC65FLAGS += -Wc --all-cdecl
+$(WORKDIR)/yaccdbg%prg: CC65FLAGS += -Wc --all-cdecl
 
 $(WORKDIR)/%.prg: %.c $(WORKDIR)/%.ref
 	$(CL65) $(CC65FLAGS) $< -o $@